The present invention relates to a tool which is particularly intended for use in refacing the counterbores formed in the cylinders of diesel engines.
The cylinders of most diesel engines are fitted with sleeves in which the pistons reciprocate and these sleeves eventually become worn and must be replaced. On the upper end of such sleeves there is an annular flange which seats in a counterbore of the cylinder. The counterbore extends from the cylinder wall to the top surface of the engine block and therefore it has a radial face parallel to that surface and a side face perpendicular to the top surface of the block. When a worn sleeve is replaced, it is common practice to reface the counterbore so that the replacement sleeve can be properly fitted into the cylinder and the annular flange will seat properly in the counterbore. This machining of the counterbore, or refacing as it is generally called, obviously is required to be done with precision since the replacement sleeve is not tightly held or correctly seated when too much metal is removed. There are tools presently available for this refacing task and usually two such tools are used, one to machine the side face of the counterbore and another to refinish the axial face of the counterbore. Such tools are costly and it has been found that a great deal of time and care must be taken in their operation if the necessary accuracy is to be achieved.